Diseases of Fruit Plantation Medicinal and Aromatic Crops

Downy mildew

Causal organism : Peronospora parasitica
Symptoms

• Initially small dots like structure are seen on the lower surface of leaves that later develop into pustules which further increase in size and produce downy growth.
• In advanced stage the leaves wither away.
• Whitish downy growth consisting of enormous amount of sporangiophores, sporangia and mycelia.
Etiology

• Aseptate mycelia, sporangiophore are at acute angle, inter cellular mycelia and intracellular haustoria.
• Asexual spores: Zoospores and sporangia.
• Sexual spores: Oospores.
• Primary source of Inoculum: Oospores present in debris.
• Secondary source of Inoculum: Zoospores
Life cycle
Epidemiology

• Temperature 18-22⁰C
• Relative humidity 95-99%
• Susceptible host.
Management

• Burn the affected debris,
• Crop rotation with non-host crop,
• Proper nutrition management
• Aerial spray of Copper oxychloride (0.3%)